When a vehicle engine is turned off, unburned fuel vapor may migrate out of the vehicle's intake manifold and cause the total vehicle hydrocarbon emissions to exceed mandated levels. There are many points on the intake manifold where the fuel vapor can escape. Some fuel vapor may be emitted through leak paths in an EGR valve.
There are devices that capture fuel vapor when the engine is off and store it for the engine to re-ingest when the engine is turned on again. These devices are associated directly with an engines air intake system and not with an EGR valve.
Thus, there is a need to provide activated carbon in leak paths of an EGR valve.